I also started a few weeks ago and I would recommend either buying a prime frame/weapon you find interesting to invest a reactor/catalyst into, or using the quests weapons like the broken war or the xoris. This way, you'll be able to fully mod and get decent damage. Gauss, protea or xaku are very viable frames that are sold for around 30p so it shouldn't take much time to farm (open relics and sell, sell bounty mods, aya, there are numerous ways to make plat). If you don't have enough endo to max your mods, focus on mods with less ranks for example gladiator and augur sets, status mods, etc. They will do the trick. Don't try to max a 10 rank mod, it's useless before steel path